1. Field of the Invention
The present invention relates to a semiconductor fabricating process. More particularly, the present invention relates to a cleaning agent and a method of removing residue after a plasma process using the cleaning agent.
2. Description of the Related Art
Due to the rapid development of integrated circuit technology, device miniaturization and integration is an inevitable trend and an important research topic in the manufacturing industry. Among the technology, dry etching technique, capable of providing an anisotropic etching process, has become one of the indispensable techniques in fabricating integrated circuits.
In the plasma etching method of a dry etching operation, plasma is used to dissociate reactive gas molecules into reactive ions capable of reacting with film material. Then, through the chemical reaction between the ions and the film layer, the thin film material exposed to the ions is transformed into a volatile substance and subsequently pumped away by a vacuum system to provide the etching process.
However, the reactive gases passing into a reaction chamber for the dry etching process may also undergo a polymerization reaction. The organic polymer formed as a result of the polymerization is deposited on the surface of the device to adversely affect a subsequent etching process. Moreover, the reactive gases used for etching the dielectric layer are mostly fluorine-containing gases. These fluorine-containing gases will react with the titanium nitride hard mask to produce titanium fluoride (TiFx) on the surface of the device, and ultimately, leading to a profile change of the device, abnormal conductivity, leakage or short-circuiting between film layers and a reduced reliability of the device.
In the fabrication of metallic interconnects, for example, the process of forming the conductive line and plug opening (a dual damascene opening) can easily produce the aforesaid polymer and titanium fluoride residues. The effect produced by these residues is particularly significant in the deep sub-micro fabrication process.
Although solvent such as ST250 can be used to improve the ‘residue’ problem, the solvent often contains expensive and dated ammonium-base compounds such as emulsifiers, restrainers and buffers. Moreover, this type of solvent can hardly remove metallic fluoride compound and the fluorine-containing particles must be removed within a designated period of time to prevent the formation of metallic fluorides. Furthermore, the type of solvent such as the ST250 will etch the metallic conductive lines and affect the conductivity of the device. Even after repeated rinsing, a portion of the organic polymer residues will still be left leading to a change of the device profile and a drop in product yield. Otherwise, a dry cleaning operation and another wet cleaning operation are required after applying the ST250 cleaning solvent. Hence, the conventional method not only is complicated but also produces additional problems. Consequently, an effective means of removing the residues left after performing a plasma manufacturing process is desired in the manufacturing industry.